The first three pearls from this week did not go out via email, although they are on


Today’s pearl:


A 45F presents with 3 weeks of CP.

Her vitals: Temp 36.8C HR 71 BP 95/65  RR 18 O2 98% RA

Her exam is unremarkable, with no signs or symptoms of DVT.

She denies hemopytsis.

She denies OCP or estrogen usage.

She denies personal hx of VTE or coagulation disorders.

She denies recent surgery.

Although the patient meets the PERC rule, a d-dimer is sent, it is positive.

A CTA Chest reveals a LUL PE.

Troponins were negative.

How can a PERC negative patient have a PE?

Click more for the answer.

The PERC rule was derived from a cohort of 8138 patients.

1666 were PERC negative, but of these 15 had DVT or PE within 45 days.

Of those 15, zero died.

We like to think of PERC negative as zero risk, but it is actually 15/1666 or .009 (<1%)

Clot creation and breakdown is a dynamic process.  If we look for it, many people without symptoms will have PE/DVT in some stage of creation/breakdown.

Given this patient’s subacute presentation and lack of signs of massive or sub-massive PE, it is possible that her PE would have resolved without any intervention.